From: Robert Klemme <bob.news@...>
Date: 2004-09-24T01:09:35+09:00
Subject: Re: whitespace string only

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<Ara.T.Howard@noaa.gov> schrieb im Newsbeitrag
news:Pine.LNX.4.60.0409230933170.2168@harp.ngdc.noaa.gov...
> On Thu, 23 Sep 2004, Robert Klemme wrote:
>
> >
> > "ts" <decoux@moulon.inra.fr> schrieb im Newsbeitrag
> > news:200409231451.i8NEphE08333@moulon.inra.fr...
> >>>>>>> "A" == Ara T Howard <Ara.T.Howard@noaa.gov> writes:
> >>
> >> A>    if s.strip.empty?
> >> A>      # the string is whitespace only
> >>
> >> svg% ruby -e 'a = " \000\000"; p "OK" if a.strip.empty?'
> >> "OK"
> >> svg%
> >>
> >> svg% ruby -e 'a = " \000\000 "; p "OK" if a.strip.empty?'
> >> svg%
> >
> > Also I'd say the disadvantage of "a.strip.empty?" is that it creates a
copy
> > of the string (=> a new instance) which is generally slower than a
simple
> > regexp check.
>
> i assumed you were correct - but this is suprising:

I have different results:

                          user     system      total        real
rx =~ s               0.031000   0.000000   0.031000 (  0.023000)
rx =~ bs              0.016000   0.000000   0.016000 (  0.022000)
rx !~ s               0.031000   0.000000   0.031000 (  0.025000)
rx !~ bs              0.016000   0.000000   0.016000 (  0.027000)
RX1 =~ s              0.031000   0.000000   0.031000 (  0.030000)
RX1 =~ bs             0.031000   0.000000   0.031000 (  0.030000)
RX2 !~ s              0.047000   0.000000   0.047000 (  0.039000)
RX2 !~ bs             0.032000   0.000000   0.032000 (  0.033000)
s =~ rx               0.031000   0.000000   0.031000 (  0.024000)
bs =~ rx              0.015000   0.000000   0.015000 (  0.024000)
s !~ rx               0.032000   0.000000   0.032000 (  0.026000)
bs !~ rx              0.031000   0.000000   0.031000 (  0.026000)
s =~ RX1              0.031000   0.000000   0.031000 (  0.031000)
bs =~ RX1             0.031000   0.000000   0.031000 (  0.031000)
s !~ RX2              0.032000   0.000000   0.032000 (  0.030000)
bs !~ RX2             0.031000   0.000000   0.031000 (  0.034000)
s.strip.empty?        0.062000   0.000000   0.062000 (  0.054000)
bs.strip.empty?       0.047000   0.000000   0.047000 (  0.050000)
                          user     system      total        real
rx =~ s               0.032000   0.000000   0.032000 (  0.022000)
rx =~ bs              0.015000   0.000000   0.015000 (  0.023000)
rx !~ s               0.031000   0.000000   0.031000 (  0.024000)
rx !~ bs              0.016000   0.000000   0.016000 (  0.025000)
RX1 =~ s              0.031000   0.000000   0.031000 (  0.030000)
RX1 =~ bs             0.032000   0.000000   0.032000 (  0.031000)
RX2 !~ s              0.031000   0.000000   0.031000 (  0.031000)
RX2 !~ bs             0.031000   0.000000   0.031000 (  0.032000)
s =~ rx               0.031000   0.000000   0.031000 (  0.025000)
bs =~ rx              0.032000   0.000000   0.032000 (  0.024000)
s !~ rx               0.015000   0.000000   0.015000 (  0.028000)
bs !~ rx              0.031000   0.000000   0.031000 (  0.026000)
s =~ RX1              0.032000   0.000000   0.032000 (  0.032000)
bs =~ RX1             0.015000   0.000000   0.015000 (  0.031000)
s !~ RX2              0.032000   0.000000   0.032000 (  0.031000)
bs !~ RX2             0.031000   0.000000   0.031000 (  0.033000)
s.strip.empty?        0.062000   0.000000   0.062000 (  0.051000)
bs.strip.empty?       0.047000   0.000000   0.047000 (  0.048000)
18:05:36 [ruby]:


Regards

    robert

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=0A=
require 'benchmark'=0A=
include Benchmark=0A=
=0A=
REP =3D 20000=0A=
=0A=
s =3D "42"=0A=
bs =3D "42" * 10000=0A=
=0A=
RX1 =3D %r{\A\s*\z}=0A=
RX2 =3D %r{\S}=0A=
=0A=
test =3D lambda do=0A=
bm(20) do |b|=0A=
  b.report "rx =3D~ s" do=0A=
    REP.times { %r{\A\s*\z} =3D~ s }=0A=
  end=0A=
=0A=
  b.report "rx =3D~ bs " do=0A=
    REP.times { %r{\A\s*\z} =3D~ bs }=0A=
  end=0A=
=0A=
  b.report "rx !~ s" do=0A=
    REP.times { %r{\S} !~ s }=0A=
  end=0A=
=0A=
  b.report "rx !~ bs " do=0A=
    REP.times { %r{\S} !~ bs }=0A=
  end=0A=
=0A=
=0A=
  b.report "RX1 =3D~ s" do=0A=
    REP.times { RX1 =3D~ s }=0A=
  end=0A=
=0A=
  b.report "RX1 =3D~ bs " do=0A=
    REP.times { RX1 =3D~ bs }=0A=
  end=0A=
=0A=
  b.report "RX2 !~ s" do=0A=
    REP.times { RX2 !~ s }=0A=
  end=0A=
=0A=
  b.report "RX2 !~ bs " do=0A=
    REP.times { RX2 !~ bs }=0A=
  end=0A=
=0A=
=0A=
  b.report "s =3D~ rx" do=0A=
    REP.times { s !~ %r{\A\s*\z} }=0A=
  end=0A=
=0A=
  b.report "bs =3D~ rx" do=0A=
    REP.times { bs =3D~ %r{\A\s*\z} }=0A=
  end=0A=
=0A=
  b.report "s !~ rx" do=0A=
    REP.times { s !~ %r{\S} }=0A=
  end=0A=
=0A=
  b.report "bs !~ rx" do=0A=
    REP.times { bs !~ %r{\S} }=0A=
  end=0A=
=0A=
  b.report "s =3D~ RX1" do=0A=
    REP.times { s !~ RX1 }=0A=
  end=0A=
=0A=
  b.report "bs =3D~ RX1" do=0A=
    REP.times { bs =3D~ RX1 }=0A=
  end=0A=
=0A=
  b.report "s !~ RX2" do=0A=
    REP.times { s !~ RX2 }=0A=
  end=0A=
=0A=
  b.report "bs !~ RX2" do=0A=
    REP.times { bs !~ RX2 }=0A=
  end=0A=
=0A=
=0A=
  b.report "s.strip.empty?" do=0A=
    REP.times { s.strip.empty? }=0A=
  end=0A=
=0A=
  b.report "bs.strip.empty?" do=0A=
    REP.times { bs.strip.empty? }=0A=
  end=0A=
end=0A=
end=0A=
=0A=
test.call=0A=
GC.disable=0A=
test.call=0A=

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